Technique for providing reliable wireless communication

ABSTRACT

A wireless device includes a first mobile equipment and a second mobile equipment sharing a single subscriber identity module. The wireless device sends a first attach request as part of a first attach procedure to a cellular network using the first mobile equipment via a first base station to establish a first communication channel to the cellular network, and sends a second attach request as part of a second attach procedure to the cellular network using the second mobile equipment via a second base station to establish a second communication channel to the cellular network. The first and second attach procedures are performed using a same subscriber identity provided by the single subscriber identity module. Upon completion of the first and second attach procedures, data communicated between the wireless device and the cellular network is transferred redundantly over the first communication channel and the second communication channel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. § 371 national stage application of PCTInternational Application No. PCT/EP2018/068646 filed on Jul. 10, 2018,the disclosure and content of which is incorporated by reference hereinin its entirety.

TECHNICAL FIELD

The present disclosure generally relates to the field of wirelesscommunication. In particular, a technique for providing reliablewireless communication between a wireless device and a cellular networkis presented. The technique may be embodied in methods, computerprograms, apparatuses and systems.

BACKGROUND

In the industrial manufacturing domain, communication capabilitiessupporting high reliability, availability as well as low anddeterministic latency are generally desired. For conventional industrialmanufacturing applications or services, these requirements are typicallymet by the provision of Industrial Ethernet (IE) solutions which arecapable of supporting grace times (i.e., times for recovery from afailure before taking emergency actions) of less than 10 ms in case ofhard real-time robot control, for example. With the rapid evolvement ofmobile communication networks and distributed devices, it is nowadaysenvisioned that Ethernet for industrial applications is replaced bywireless networks, such as 4G or 5G networks, for example.

In the context of conventional 3GPP networks, however, whenever a nodefailure or communication link failure occurs, Radio Resource Control(RRC) procedures including Non-Access Stratum (NAS) security setup andauthentication procedures generally start over. These procedures mayrequire multiple roundtrips incurring latency and may therefore resultin loss of availability for an application or service running on top ofthe radio connection due to the reattachment of the User Equipment (UE)to the network. Signaling involved in these procedures may be seen inFIG. 1 which illustrates a conventional 3GPP network attach procedure.It will be understood that the shown attach procedure is simplified andonly focuses on those aspects which are relevant in the context of thepresent disclosure.

As may be seen in FIG. 1, a network attach generally starts with the UEsending an attach request to the eNodeB (eNB) containing the identity ofthe UE, e.g., an International Mobile Subscriber Identity (IMSI), aswell as the UE network capabilities. It is noted in this regard that, asunderstood herein, the UE corresponds to a combination of a MobileEquipment (ME) and a Universal Subscriber Identity Module (USIM). FIG. 1thus indicates the ME and the USIM as separate entities, which togetherrepresent the UE. The eNB forwards the information received from the UEto the Mobility Management Entity (MME) which, based on the IMSI,requests authentication vectors (AVs) from the Home Subscriber Server(HSS). The HSS, in turn, provides a set of AVs to the MME, eachcontaining authentication-related data including an authentication token(AUTN) for authenticating the network, a random number (RAND)representing a challenge to the UE, an expected response (XRES)representing an expected response to the challenge, and an accesssecurity management entity key (K_(ASME)) representing a root key to beused by the MME for the specific AV. The MME then sends, via the eNB, anauthentication request to the UE containing the AUTN and the RAND. TheUSIM verifies the AUTN, generates a Cipher Key (CK) and an Integrity Key(IK) and computes a response (RES) to the challenge. The ME obtainsthese keys from the USIM and sends the RES to the MME. The ME alsocomputes the K_(ASME) from the obtained keys. The MME then verifieswhether the received result RES matches the expected result XRES and, ifthere is a match, the UE is considered to be authenticated. As indicatedin FIG. 1, this procedure corresponds to a standard Authentication andKey Agreement (AKA) procedure.

Subsequently, the MME sends a NAS security mode command to the UEindicating which algorithms are to be used for NAS signaling. Based onthis, the ME generates the NAS keys and then sends a NAS security modecomplete message back to the MME. At this point, NAS security isconfigured and NAS signaling ends. The MME then generates an eNB key(keNB) and sends it to the eNB in an attach accept message together withthe UE network capabilities. The eNB uses the received information forthe generation of Access Stratum (AS) keys and then sends an AS securitymode command to the UE. The UE, in turn, generates corresponding keysand responds with an AS security mode complete message. At this point,AS security is configured and AS security signaling ends. Meanwhile, theMME has configured a General Packet Radio Service (GPRS) TunnelingProtocol (GTP) tunnel for the UE at the Packet Gateway (PGW) of thenetwork.

Again, once a UE connection fails due to a local error or an eNBfailure, such attach procedure starts over and incurs delay that isnoticed by the service or application running on top, which mayeventually result in loss of availability. Such situation couldgenerally be addressed by having two redundant UEs with two independentSubscriber Identity Module (SIM) cards, wherein each UE runs the sameapplication or service. However, in such a case, the HSS needs tomaintain multiple entries for both UEs and a server communicating withthe UEs receives all traffic duplicated from two different flows,potentially creating problems regarding the internal state of theserver. Also, the two UEs would typically connect to the same eNB sothat, when the eNB fails, availability may still be lost. Anothersolution may be Dual Connectivity, a feature introduced with Long TermEvolution (LTE) networks, according to which the UE is connected to twoeNBs simultaneously, i.e., a Master eNB (MeNB) and a Secondary eNB(SeNB), which operate on different carrier frequencies and areinterconnected by traditional backhaul link interfaces. In DualConnectivity, the RRC connection is maintained via the MeNB, while datatraffic can go from the Serving Gateway (SGW) to both the MeNB and theSeNB, or it can go to the MeNB and can further be split from the MeNB tothe SeNB, as shown in FIG. 2. However, in Dual Connectivity, there isonly a single UE which represents a single point of failure and,therefore, Dual Connectivity cannot provide ultimate reliability inwireless communication either.

SUMMARY

Accordingly, there is a need for a technique that improves reliabilityof wireless communication in a wireless communication system.

According to a first aspect, a method for providing reliable wirelesscommunication between a wireless device and a cellular network isprovided. The wireless device comprises a first mobile equipment and asecond mobile equipment sharing a single subscriber identity module. Themethod is performed by the wireless device and comprises sending a firstattach request as part of a first attach procedure to the cellularnetwork using the first mobile equipment via a first base station toestablish a first communication channel to the cellular network, sendinga second attach request as part of a second attach procedure to thecellular network using the second mobile equipment via a second basestation to establish a second communication channel to the cellularnetwork, wherein the first attach procedure and the second attachprocedure are performed using a same subscriber identity provided by thesingle subscriber identity module and wherein, upon completion of thefirst attach procedure and the second attach procedure, datacommunicated between the wireless device and the cellular network istransferred redundantly over the first communication channel and thesecond communication channel.

The wireless device may serve as wireless communication gateway for abase application, wherein data transferred redundantly from the wirelessdevice to the cellular network may originate from the base application.Data originating from the base application may be duplicated by aredundancy component before being transferred to the cellular networkover the first communication channel and the second communicationchannel. Duplicate data transferred from the cellular network to thewireless device over the first communication channel and the secondcommunication channel may be dropped by a redundancy component beforeforwarding the transferred data to the base application. The baseapplication may be controlled by a network-side application via thecellular network.

The second attach request may be sent upon completion of the firstattach procedure. In at least one of the first and the second attachprocedure, a dual mode indication may be sent from the wireless deviceto the cellular network indicating that the wireless device intends totransfer data redundantly over the first communication channel and thesecond communication channel. Also, authentication-related data used inthe first attach procedure may be reused in the second attach procedure,wherein the authentication-related data reused in the second attachprocedure may comprise a set of authentication vectors stored by thecellular network in the first attach procedure. From the set ofauthentication vectors, an authentication vector already used in thefirst attach procedure may be reused for the second attach procedure, oran authentication vector different from an authentication vector used inthe first attach procedure may be used in the second attach procedure.An authentication request sent from the cellular network to the secondmobile equipment may then include a maintenance indication indicating tothe wireless device to maintain a context already established for thefirst mobile equipment in the first attach procedure.

Alternatively or additionally, the authentication-related data reused inthe second attach procedure may comprise authentication-related datastored by the wireless device in the first attach procedure. At leastpart of the authentication-related data or data derived therefrom maythen be included in the second attach request. Also, as part of thesecond attach procedure, an authentication request for authenticatingthe second mobile equipment may be sent from the cellular network to thefirst mobile equipment, wherein the first mobile equipment may triggerverification of whether the authentication request belongs to the secondattach procedure. An authentication response to the authenticationrequest may then be sent to the cellular network by at least one of thefirst mobile equipment and the second mobile equipment.

According to a second aspect, a method for providing reliable wirelesscommunication between a wireless device and a cellular network isprovided. The method is performed by a node of the cellular network andcomprises receiving a first attach request from a first mobile equipmentof the wireless device via a first base station as part of a firstattach procedure to establish a first communication channel between thecellular network and the wireless device, receiving a second attachrequest from a second mobile equipment of the wireless device via asecond base station as part of a second attach procedure to establish asecond communication channel between the cellular network and thewireless device, wherein, in the first attach procedure and the secondattach procedure, a same subscriber identity is used and wherein, uponcompletion of the first attach procedure and the second attachprocedure, data communicated between the wireless device and thecellular network is transferred redundantly over the first communicationchannel and the second communication channel.

The method according to the second aspect defines a method from theperspective of a node of the cellular network which may be complementaryto the method performed by the wireless device according to the firstaspect. Thus, as in the method of the first aspect, the second attachrequest may be received upon completion of the first attach procedureand, in at least one of the first and the second attach procedure, adual mode indication may be received by the node from the wirelessdevice indicating that the wireless device intends to transfer dataredundantly over the first communication channel and the secondcommunication channel. Also, authentication-related data used in thefirst attach procedure may be reused in the second attach procedure,wherein the authentication-related data reused in the second attachprocedure may comprise a set of authentication vectors stored by thenode in the first attach procedure. From the set of authenticationvectors, an authentication vector already used in the first attachprocedure may be reused for the second attach procedure, or anauthentication vector different from an authentication vector used inthe first attach procedure may be used in the second attach procedure.An authentication request sent from the node to the second mobileequipment may then include a maintenance indication indicating to thewireless device to maintain a context already established for the firstmobile equipment in the first attach procedure.

Alternatively or additionally, the authentication-related data reused inthe second attach procedure may comprise authentication-related datastored by the wireless device in the first attach procedure. At leastpart of the authentication-related data or data derived therefrom maythen be included in the second attach request. Also, as part of thesecond attach procedure, an authentication request for authenticatingthe second mobile equipment may be sent from the node to the firstmobile equipment. An authentication response to the authenticationrequest may then be received by the node from at least one of the firstmobile equipment and the second mobile equipment. Upon completion of thefirst attach procedure and the second attach procedure, the node maysend a redundancy indication to a gateway of the cellular networkindicating that data transferred over the first communication channeland the second communication channel is transferred redundantly.

According to a third aspect, a method for providing reliable wirelesscommunication between a wireless device and a cellular network isprovided. The method is performed by a gateway of the cellular networkand comprises receiving first data over a first communication channelestablished between a first mobile equipment of the wireless device andthe cellular network via a first base station, receiving second dataover a second communication channel established between a second mobileequipment of the wireless device and the cellular network via a secondbase station, wherein the first data and the second data are associatedwith a same subscriber identity and wherein the first data and thesecond data are transferred redundantly over the first communicationchannel and the second communication channel, and dropping duplicatedata from the first data and the second data before forwarding thetransferred data to a network-side application.

The method according to the third aspect defines a method from theperspective of a gateway of the cellular network which may becomplementary to the method performed by the wireless device accordingto the first aspect and/or the method performed by the node according tothe second aspect. Thus, data to be transferred from the network-sideapplication to the wireless device may be duplicated by the gatewaybefore being transferred to the wireless device over the firstcommunication channel and the second communication channel. As in themethod of the second aspect, the gateway may receive a redundancyindication from a node of the cellular network indicating that datatransferred over the first communication channel and the secondcommunication channel is transferred redundantly. Upon receiving theredundancy indication, the gateway may prevent deleting a contextestablished for the first data when a context of the second datacollides with the context of the first data. The redundancy indicationmay be provided in the form of an extension field included in a sessioncreation request message of an existing session creation protocol, orthe redundancy indication may be provided in the form of a dedicatedsession creation request message extending an existing session creationprotocol.

According to a fourth aspect, a computer program product is provided.The computer program product comprises program code portions forperforming the method of at least one of the first, the second and thethird aspect when the computer program product is executed on one ormore computing devices (e.g., a processor or a distributed set ofprocessors). The computer program product may be stored on a computerreadable recording medium, such as a semiconductor memory, DVD, CD-ROM,and so on.

According to a fifth aspect, a wireless device for providing reliablewireless communication to a cellular network is provided. The wirelessdevice comprises a first mobile equipment and a second mobile equipmentsharing a single subscriber identity module, and the wireless device isconfigured to perform any of the method steps presented herein withrespect to the first aspect. The wireless device may comprise at leastone processor and at least one memory, wherein the at least one memorycontains instructions executable by the at least one processor such thatthe wireless device is operable to perform any of the method stepspresented herein with respect to the first aspect.

According to a sixth aspect, a node of a cellular network for providingreliable wireless communication between a wireless device and thecellular network is provided. The node is configured to perform any ofthe method steps presented herein with respect to the second aspect. Thenode may comprise at least one processor and at least one memory,wherein the at least one memory contains instructions executable by theat least one processor such that the node is operable to perform any ofthe method steps presented herein with respect to the second aspect.

According to a seventh aspect, a gateway of a cellular network forproviding reliable wireless communication between a wireless device andthe cellular network is provided. The gateway is configured to performany of the method steps presented herein with respect to the thirdaspect. The gateway may comprise at least one processor and at least onememory, wherein the at least one memory contains instructions executableby the at least one processor such that the gateway is operable toperform any of the method steps presented herein with respect to thethird aspect.

According to an eighth aspect, there is provided a system comprising awireless device according to the fifth aspect, a node according to thesixth aspect and, optionally, a gateway according to the seventh aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Various implementations of the technique presented herein are describedherein below with reference to the accompanying drawings, in which:

FIG. 1 illustrates a signaling diagram of an exemplary network attachprocedure in a conventional 3GPP network;

FIG. 2 schematically illustrates variants of conventional DualConnectivity architectures in an LTE network;

FIGS. 3a to 3c illustrate exemplary compositions of a wireless device, anode of a cellular network and a gateway of a cellular network accordingto the present disclosure;

FIG. 4 illustrates a method embodiment which may be performed by thewireless device;

FIGS. 5a and 5b illustrate a modular composition of the node and acorresponding method embodiment which may be performed by the node;

FIGS. 6a and 6b illustrate a modular composition of the gateway and acorresponding method embodiment which may be performed by the gateway;

FIG. 7 illustrates an exemplary system in which a network-sideapplication controls a base application using redundant connectivityprovided by a wireless device and a cellular network according to thepresent disclosure;

FIG. 8 schematically illustrates an exemplary detailed view of a firstmobile equipment and a second mobile equipment interfacing with a singlesubscriber identity module;

FIG. 9 illustrates a signaling diagram of an example of the first attachprocedure according to the present disclosure;

FIG. 10 illustrates a signaling diagram of a first exemplary variant ofthe second attach procedure according to the present disclosure;

FIG. 11 illustrates a signaling diagram of a second exemplary variant ofthe second attach procedure according to the present disclosure;

FIG. 12 illustrates a signaling diagram of a third exemplary variant ofthe second attach procedure according to the present disclosure;

FIG. 13 illustrates a signaling diagram of a fourth exemplary variant ofthe second attach procedure according to the present disclosure;

FIG. 14 illustrates a signaling diagram of a first exemplary procedurefor providing a redundancy indication to the gateway according to thepresent disclosure; and

FIG. 15 illustrates a signaling diagram of a second exemplary procedurefor providing a redundancy indication to the gateway according to thepresent disclosure.

DETAILED DESCRIPTION

In the following description, for purposes of explanation and notlimitation, specific details are set forth in order to provide athorough understanding of the present disclosure. It will be apparent toone skilled in the art that the present disclosure may be practiced inother embodiments that depart from these specific details. For example,while specific implementations will be described with reference tocertain variants of 4G networks, it will be understood that the presentdisclosure shall not be limited thereto and that the technique presentedherein may be practiced in other variants of wireless communicationnetworks.

Those skilled in the art will further appreciate that the steps,services and functions explained herein below may be implemented usingindividual hardware circuitry, using software functioning in conjunctionwith a programmed micro-processor or general purpose computer, using oneor more Application Specific Integrated Circuits (ASICs) and/or usingone or more Digital Signal Processors (DSPs). It will also beappreciated that when the present disclosure is described in terms of amethod, it may also be embodied in one or more processors and one ormore memories coupled to the one or more processors, wherein the one ormore memories are encoded with one or more programs that perform thesteps, services and functions disclosed herein when executed by the oneor more processors.

FIG. 3a schematically illustrates an exemplary composition of a wirelessdevice 300 for providing reliable wireless communication to a cellularnetwork. The wireless device 300 comprises at least one processor 302and at least one memory 304, wherein the at least one memory 304contains instructions executable by the at least one processor 302 suchthat the wireless device 300 is operable to carry out the method stepsdescribed herein below. The wireless device 300 further comprises afirst mobile equipment 306 and a second mobile equipment 308 which sharea single subscriber identity module 309. These will be described in moredetail below.

FIG. 3b schematically illustrates an exemplary composition of a node 310of a cellular network for providing reliable wireless communicationbetween a wireless device and a cellular network. The node 310 comprisesat least one processor 312 and at least one memory 314, wherein the atleast one memory 314 contains instructions executable by the at leastone processor 312 such that the node 310 is operable to carry out themethod steps described herein below.

FIG. 3c schematically illustrates an exemplary composition of a gateway320 of a cellular network for providing reliable wireless communicationbetween a wireless device and a cellular network. The gateway 320comprises at least one processor 322 and at least one memory 324,wherein the at least one memory 324 contains instructions executable bythe at least one processor 322 such that the gateway 320 is operable tocarry out the method steps described herein below.

It will be understood that at least one of the node 310 and the gateway320 may be implemented as a physical computing unit as well as avirtualized computing unit, such as a virtual machine, for example. Itwill further be appreciated that at least one of the node 310 and thegateway 320 may not necessarily be implemented as a standalone computingunit, but may be implemented as components—realized in software and/orhardware—residing on multiple distributed computing units as well, suchas in a cloud computing environment, for example.

FIG. 4 illustrates a method for providing reliable wirelesscommunication between the wireless device 300 and a cellular networkwhich may be performed by the wireless device 300 and which will be usedin the following to describe the basic operation of the wireless device300.

In step S402, the wireless device 300 sends a first attach request aspart of a first attach procedure to the cellular network using the firstmobile equipment 306 via a first base station to establish a firstcommunication channel to the cellular network. In step S404, thewireless device 300 sends a second attach request as part of a secondattach procedure to the cellular network using the second mobileequipment 308 via a second base station to establish a secondcommunication channel to the cellular network. The first attachprocedure and the second attach procedure are performed using a samesubscriber identity provided by the single subscriber identity module309 and, upon completion of the first attach procedure and the secondattach procedure, data communicated between the wireless device 300 andthe cellular network is transferred redundantly over the firstcommunication channel and the second communication channel. In stepS406, the wireless device 300 may thus exchange (i.e., send and/orreceive) data between the wireless device 300 and cellular networkredundantly over the first communication channel and the secondcommunication channel. More specifically, the wireless device 300 maysend or receive first data over the first communication channel and maysend or receive second data over the second communication channel to thecellular network, wherein the first data and the second data aretransferred redundantly. In the cellular network, the first data and thesecond data may be received by a gateway, such as gateway 320, whichhandles the redundantly transferred data on the network side before thetransferred data is forwarded its destination (e.g., a network-sideapplication), as will be described below. The first base station and thesecond base station may be different so that the first communicationchannel and the second communication channel may correspond to separate(e.g., physically separated) communication paths.

The first mobile equipment 306 and the second mobile equipment 308 maycorrespond to separate MEs (e.g., self-contained and independentlyoperable MEs) included in the wireless device 300, which both have aninterface to the single subscriber identity module 309 so that thesingle subscriber identity module 309 can be used as a common subscriberidentity module by both MEs. The single subscriber identity module 309may be a Universal Integrated Circuit Card (UICC) module which runs aUSIM application, wherein the USIM application may record user specificdata, such as an IMSI, a phone number, and a unique private key, forexample. The single subscriber identity module 309 may generate keys forthe AKA procedures of the first mobile equipment 306 and the secondmobile equipment 308, e.g., based on the single unique private keyrecorded by the USIM application. The single subscriber identity module309 may provide the same subscriber identity (e.g., IMSI) to both thefirst mobile equipment 306 and the second mobile equipment 308 for usein the first attach procedure and the second attach procedure, therebyenabling the cellular network to perceive both the first mobileequipment 306 and the second mobile equipment 308 as a single entity.

It will be understood that the first mobile equipment 306 and the secondmobile equipment 308 do not necessarily have to be provided as separateself-contained MEs, but may also be realized as virtual MEs implemented(e.g., software-based) on a single physical ME of the wireless device300, wherein the single physical ME may create multiple contexts withthe cellular network via different base stations and may have two radiointerfaces for this purpose (e.g., on two different chipsets). Thecellular network may be any type of cellular wireless network, such as a4G or 5G network, for example, and the first base station and the secondbase station may be an eNB or gNB (next generation NodeB) accordingly.

The data communicated between the wireless device 300 and the cellularnetwork may be part of an end-to-end communication being performedbetween a device-side application and a network-side application overthe cellular network (e.g., between a client application communicatingwith an Internet-based server application via the cellular network). Thewireless device 300 may thus serve as wireless communication gateway fora base application (i.e., the device-side application), wherein datatransferred redundantly from the wireless device 300 to the cellularnetwork originates from the base application. The base application maybe executed on the wireless device 300 itself or on a base device (i.e.,a device separate from the wireless device) that uses the wirelessdevice 300 as gateway device to communicate via the cellular network.The first mobile equipment 306 and the second mobile equipment 308 maythus be said to provide redundant connectivity to the same applicationor device.

Data originating from the base application may be duplicated by aredundancy component before being transferred by the wireless device 300to the cellular network over the first communication channel and thesecond communication channel (for further delivery to the network-sideapplication, for example). Similarly, duplicate data transferred fromthe cellular network to the wireless device 300 over the firstcommunication channel and the second communication channel (e.g., dataoriginating from the network-side application) may be dropped by theredundancy component before forwarding the transferred data to the baseapplication. In other words, the redundancy component may ensure thatdata packets outgoing from the base application are copied before beingtransferred by the wireless device 300 over the cellular network andthat duplicated data packets incoming from the cellular network aredropped so that only one copy of each incoming data packet is forwardedto the base application (i.e., one redundant packet is dropped and oneis forwarded so that the redundant data flow is filtered down to asingle flow). In this way, the base application may be agnostic of theredundant data transfer and the redundancy component may thus be said tohide the redundant wireless connectivity function from the baseapplication.

In one such variant, the redundancy component may not wait untilduplicated data packets are received (i.e., until both copies of aredundantly transferred packet are received), but may immediatelyforward the first copy of a redundantly transferred packet to the baseapplication and may keep information on the first copy (e.g., based onsequence numbers used in packet headers or hashes) for some time anddrop the second copy of the redundantly transferred packet, if the firstcopy has already been seen. In this way, latency in forwarding thepackets may be reduced. The redundancy component may be part of thewireless device 300 or may be a component separate from the wirelessdevice 300, such as a component executed on the base device, forexample.

In one implementation, the base application may be controlled by thenetwork-side application via the cellular network. For example, when thebase application is executed on an industrial machine (the industrialmachine may then be the base device) and the network-side applicationcorresponds to an industrial machine controller (e.g., executed in acloud computing environment), the industrial machine may be controlledby the industrial machine controller using the reliable wirelessconnection provided by the wireless device 300 and the cellular network.In a cloud robotics system, a robot controller (corresponding to thenetwork-side application) may control a robot sensor (corresponding tothe base application) over the cellular network, for example.

As to the attach procedures performed by the wireless device 300, boththe first attach procedure and the second attach procedure mayessentially take the form of the conventional network attach proceduredescribed above. It is again referred to the description of FIG. 1 inthis regard and unnecessary repetitions are omitted at this point.Modifications to this procedure may be required, however, in order toimplement the technique presented herein. These modifications—as it maybe the case for the first attach procedure and the second attachprocedure, respectively—will be outlined below.

The first and the second attach procedure may be performedconsecutively, e.g., the second attach request may be sent uponcompletion of the first attach procedure. In this way, the wirelessdevice 300 may ensure that the second mobile equipment 308 does notattach to the cellular network via the first base station, but viaanother base station, so that it is made sure that the first basestation and the second base station differ and that physically separatedcommunication paths are provided, as described above.

As an exemplary modification to the conventional network attachprocedure of FIG. 1, a dual mode indication may be sent, in at least oneof the first and the second attach procedure, from the wireless device300 to the cellular network indicating that the wireless device 300intends to transfer data redundantly over the first communicationchannel and the second communication channel. In this way, the cellularnetwork may be enabled to take preparatory measures to handle theredundantly transferred data on the network side. The dual modeindication may be included (e.g., in the form of a flag) in at least oneof the first and the second attach request (e.g., as part of the UEnetwork capabilities) or in the NAS security mode complete message sentfrom the UE to the cellular network (e.g., the MME), for example.

In order to ease the AKA procedures when attaching twice, i.e., in thefirst and the second attach procedure, and to reduce correspondingsignaling if possible, authentication-related data used in the firstattach procedure may be reused in the second attach procedure. Theauthentication-related data may be data other than the subscriberidentity provided by the single subscriber identity module 309. In oneimplementation, the authentication-related data reused in the secondattach procedure may comprise a set of authentication vectors (AVs)stored by the cellular network (e.g., by the MME) in the first attachprocedure. For such reuse, the cellular network (e.g., the MME) maystore the set of authentication vectors (e.g., as obtained from an HSSof the cellular network) in a database in the first attach procedure andmay retrieve the set of authentication vectors from the database ifneeded in the second attach procedure. The database may be a databasededicated to be used for the dual mode technique described herein.

In one variant of reusing the set of authentication vectors, thecellular network (e.g., the MME) may select, from the set ofauthentication vectors, the same authentication vector as for the firstmobile equipment 306. The second mobile equipment 308 may thus receivean authentication request from the cellular network with the same RANDand AUTN as in the first attach procedure, resulting in the same keysbeing used by the second mobile equipment 308, e.g., the CK and IKcomputed by the single subscriber identity module 309 in the firstattach procedure may be reused for the second attach procedure. In otherwords, from the set of authentication vectors, an authentication vectoralready used in the first attach procedure may be reused for the secondattach procedure. In order to protect against authentication replyre-transmission by an attacker, a security measure may be employed inthis case, such as—considering the second use of the same authenticationvector—making responses to the second authentication look differently,e.g., by encrypting the RES with K_(ASME) and sending the encrypted RESinstead of the plaintext RES.

In another variant of reusing the set of authentication vectors, thecellular network (e.g., the MME) may select, from the set ofauthentication vectors, an authentication vector different from the oneused for the first mobile equipment 306, resulting in the second mobileequipment 308 receiving an authentication request with a different RANDand AUTN as well as different keys being used by the second mobileequipment 308. In this variant, from the set of authentication vectors,an authentication vector different from an authentication vector used inthe first attach procedure may be used in the second attach procedure.An authentication request sent from the cellular network (e.g., the MME)to the second mobile equipment 308 may in this case include amaintenance indication indicating to the wireless device 300 to maintaina context already established for the first mobile equipment 306 in thefirst attach procedure. In this way, it may be ensured that a contextalready established for the first mobile equipment 306 is kept aliveeven if a new attach/AKA procedure is performed by the wireless device300.

Alternatively or additionally, the authentication-related data reused inthe second attach procedure may comprise authentication-related datastored by the wireless device 300 in the first attach procedure. Atleast part of the authentication-related data or data are derivedtherefrom may then be included in the second attach request. In otherwords, the second mobile equipment 308 may reuse authentication-relateddata already known from the first attach procedure and may provide suchdata or a derivative therefrom to the cellular network (e.g., the MME)with the second attach request, enabling the cellular network toauthenticate the second mobile equipment 308 instantly without the needfor further signaling, such as an authentication request/responsescheme, for example. As an example, the second mobile equipment 308 mayuse the CK and IK computed by the single subscriber identity module 309in the first attach procedure for the generation of the K_(ASME) andsign the RAND with it, thereby creating a derivative of theauthentication-related data (optionally, not only the RAND may beencrypted with the K_(ASME), but also the RAND together with a devicegenerated nonce in order to protect against an attacker replaying thismessage at a later point of time). The signed RAND may then be includedin the second attach request and the cellular network (e.g., the MME)may, in order to authenticate the second mobile equipment 308, verifythat the RAND is the one used by the first mobile equipment 306 and issigned by the K_(ASME) of the first mobile equipment 306.

In another implementation, an authentication request for authenticatingthe second mobile equipment 308 may be sent, as part of the secondattach procedure, from the cellular network (e.g., the MME) to the firstmobile equipment 306 (i.e., different from where it received the secondattach request), wherein the first mobile equipment 306 may triggerverification of whether the authentication request belongs to the secondattach procedure. This may include checking by the wireless device 300whether the second mobile equipment 308 has sent the second attachrequest, for example. In this way, attacks by random users trying toexploit the dual mode function and attempting to pretend to be thesecond mobile equipment 308 may be prevented. The authenticationresponse to the authentication request may then be sent to the cellularnetwork (e.g., the MME) by at least one of the first mobile equipment306 and the second mobile equipment 308.

FIG. 5a schematically illustrates an exemplary modular composition ofthe node 310 of the cellular network and FIG. 5b illustrates acorresponding method which may be performed by the node 310. The basicoperation of the node 310 will be described in the following withreference to both FIGS. 5a and 5b . This operation may be complementaryto the operation of the wireless device 300 described above in relationto FIG. 4 and, as such, aspects described above with regard to thecellular network (in particular the MME) may be applicable to the node310 described in the following as well, and vice versa. Unnecessaryrepetitions are thus omitted. The node 310 may be a mobility managemententity, such as an MME in a 4G network or an Access and MobilityFunction (AMF) in a 5G network, for example.

In step S502, a first receiving module 502 of the node 310 may receive afirst attach request from the first mobile equipment 306 of the wirelessdevice 300 via the first base station as part of the first attachprocedure to establish the first communication channel between thecellular network and the wireless device 300. In step S504, a secondreceiving module 504 may receive a second attach request from the secondmobile equipment 308 of the wireless device 300 via the second basestation as part of the second attach procedure to establish the secondcommunication channel between the cellular network and the wirelessdevice 300. In the first attach procedure and the second attachprocedure, the same subscriber identity is used and, upon completion ofthe first attach procedure and the second attach procedure, datacommunicated between the wireless device 300 and the cellular network istransferred redundantly over the first communication channel and thesecond communication channel.

As in the method of FIG. 4, the second attach request may be receivedupon completion of the first attach procedure. In at least one of thefirst and the second attach procedure, a dual mode indication may bereceived by the node 310 from the wireless device 300 indicating thatthe wireless device 300 intends to transfer data redundantly over thefirst communication channel and the second communication channel. Also,authentication-related data used in the first attach procedure may bereused in the second attach procedure, wherein theauthentication-related data reused in the second attach procedure maycomprise a set of authentication vectors stored by the node 310 in thefirst attach procedure. From the set of authentication vectors, anauthentication vector already used in the first attach procedure may bereused for the second attach procedure, or an authentication vectordifferent from an authentication vector used in the first attachprocedure may be used in the second attach procedure. An authenticationrequest sent from the node 310 to the second mobile equipment 308 maythen include a maintenance indication indicating to the wireless device300 to maintain a context already established for the first mobileequipment 306 in the first attach procedure.

Alternatively or additionally, the authentication-related data reused inthe second attach procedure may comprise authentication-related datastored by the wireless device 300 in the first attach procedure. Atleast part of the authentication-related data or data derived therefrommay then be included in the second attach request. Also, as part of thesecond attach procedure, an authentication request for authenticatingthe second mobile equipment 308 may be sent from the node 310 to thefirst mobile equipment 306. An authentication response to theauthentication request may then be received by the node 310 from atleast one of the first mobile equipment 306 and the second mobileequipment 308.

In order to take preparatory measures so that the cellular network maycorrectly handle redundantly transferred data received from the wirelessdevice 300 over the first communication channel and the secondcommunication channel, the node 310 may establish a context (andconfigure a corresponding GTP tunnel, for example) for each of the firstmobile equipment 306 and the second mobile equipment 308 in a gateway,such as the gateway 320 of the cellular network, for example. Toindicate to the gateway that the contexts (and the GTP tunnels, forexample) of the first mobile equipment 306 and the second mobileequipment 308 are to be linked together, the node 310 may send, uponcompletion of the first attach procedure and the second attachprocedure, a redundancy indication to the gateway of the cellularnetwork indicating that data transferred over the first communicationchannel and the second communication channel is transferred redundantly.

FIG. 6a schematically illustrates an exemplary modular composition ofthe gateway 320 of the cellular network and FIG. 6b illustrates acorresponding method which may be performed by the gateway 320. Thebasic operation of the gateway 320 will be described in the followingwith reference to both FIGS. 6a and 6b . This operation may becomplementary to the operation of the wireless device 300 and the node310 described above in relation to FIG. 4 as well as FIGS. 5a and 5band, as such, aspects described above with regard to the gateway may beapplicable to the gateway 320 described in the following as well, andvice versa. Unnecessary repetitions are thus omitted. The gateway 320may be a packet gateway, such as a PGW in a 4G network or a User PlaneFunction (UPF) in a 5G network, for example.

In step S602, a first receiving module 602 of the gateway 320 mayreceive first data over the first communication channel establishedbetween the first mobile equipment 306 of the wireless device 300 andthe cellular network via the first base station. In step S604, a secondreceiving module 604 of the gateway 320 may receive second data over thesecond communication channel established between the second mobileequipment 308 of the wireless device 300 and the cellular network viathe second base station. The first data and the second data areassociated with a same subscriber identity and the first data and thesecond data are transferred redundantly over the first communicationchannel and the second communication channel. In step S606, a redundancymodule 606 of the gateway 320 may drop duplicate data from the firstdata and the second data before forwarding the transferred data to anetwork-side application. Also, data to be transferred from thenetwork-side application to the wireless device 300 may be duplicated bythe redundancy module 606 of the gateway 320 before being transferred tothe wireless device 300 over the first communication channel and thesecond communication channel. Once duplicated, the gateway 320 may sendthe resulting data redundantly over the first communication channel andthe second communication channel to the wireless device 300.

As described above, data communicated between the wireless device 300and the cellular network may be part of an end-to-end communicationbeing performed between a base application and the network-sideapplication. The redundancy module 606 of the gateway 320 may thusensure that data packets outgoing from the network-side application arecopied before being forwarded by the gateway 320 to the wireless device300 and that duplicated data packets incoming from the wireless device300 are dropped so that only one copy of each incoming data packet isforwarded to the network-side application (i.e., one redundant packet isdropped and one is forwarded so that the redundant data flow is filtereddown to a single flow). In this way, the network-side application may beagnostic of the redundant data transfer and the gateway 320 may thus besaid to hide the redundant wireless connectivity function from thenetwork-side application.

In one such variant, the gateway 320 may not wait until duplicated datapackets are received (i.e., until both copies of a redundantlytransferred packet are received), but may immediately forward the firstcopy of a redundantly transferred packet to the network-side applicationand may keep information on the first copy (e.g., based on sequencenumbers used in packet headers or hashes) for some time and drop thesecond copy of the redundantly transferred packet, if the first copy hasalready been seen. In this way, latency in forwarding the packets may bereduced.

In accordance with the method of FIGS. 5a and 5b , the gateway 320 mayreceive a redundancy indication from the node 310 of the cellularnetwork indicating that data transferred over the first communicationchannel and the second communication channel is transferred redundantly.Upon receiving the redundancy indication, the gateway 320 may installpacket filtering rules to implement the packet dropping and duplicatingbehavior described above. Upon receiving the redundancy indication, thegateway 320 may further prevent deleting a context established for thefirst data when a content of the second data collides with the contextof the first data. This may be necessary because conventional cellularnetworks may implement a behavior according to which an already existingcontext/session is deleted before creating a new context/session if thecreation request collides with the existing context/session (e.g., whenboth contexts/sessions are mapped to the same IMSI). The redundancyindication may be provided in the form of an extension field included ina session creation request message of an existing session creationprotocol, or in the form of a dedicated session creation request messageextending an existing session creation protocol, for example.

While, in the above implementations, the technique presented herein hasbeen described for redundant wireless connectivity using two redundantcommunication channels, i.e., the first communication channel and thesecond communication channel, it will be understood that the presentedtechnique may generally be employed with N, where N>2, redundantcommunication channels, wherein the additional redundant communicationchannels may be subject to the principles discussed above for the firstcommunication channel and the second communication channel as well.

The following FIGS. 7 to 15 illustrate exemplary embodiments of thetechnique presented herein which elucidate certain aspects of the aboveimplementations in more detail.

FIG. 7 illustrates an exemplary system in which a wireless device 702and a cellular network 704 provide redundant wireless connectivitybetween a base application 706 and a network-side application 708 (e.g.,between a robot sensor and a robot controller, as shown in the figure).The wireless device 702 may correspond to the wireless device 300 andcomprises a first mobile equipment 710 and a second mobile equipment 712sharing a single subscriber identity module 713 (e.g., a UICC module, asshown in the figure). In the shown example, the cellular network is a 4Gnetwork and comprises an MME 714 (corresponding to the node 310) as wellas a PGW 716 (corresponding to the gateway 320). As may be seen in thefigure, data communicated between the base application 706 and thenetwork-side application 708 is transferred redundantly over a firstcommunication channel (or path) provided between the first mobileequipment 710 and the PGW 716 via a first base station 718 and a firstSGW 720 as well as over a second communication channel (or path)provided between the second mobile equipment 712 and the PGW 716 via asecond base station 722 and a second SGW 724. A redundancy component 726is provided between the base application 706 and the wireless device 702to hide the redundant wireless connectivity function from the baseapplication 706, as described above. While, in the example of FIG. 7,the redundancy component 726 is external to the wireless device 702, itwill be understood that the redundancy component 726 may also beincluded in the wireless device 702. Further, the MME 714 is connectedto an HSS 728. Exemplary signaling between the entities shown in FIG. 7will be described below with reference to FIGS. 9 to 15.

FIG. 8 schematically illustrates an exemplary detailed view of the firstmobile equipment 710 and the second mobile equipment 712 (includingtheir radio stacks) interfacing with the single subscriber identitymodule 713 (shown as common USIM application). As indicated in figure,the individual security modules of the first mobile equipment 710 andthe second mobile equipment 712 may interact with the common USIMapplication 713 to obtain and derive keys, such as the CK, IK andK_(ASME) enabling ciphering and integrity checks and various layers,such as PDCP, for example.

FIG. 9 illustrates a signaling diagram of an example of the first attachprocedure performed by the first mobile equipment 710. The procedureshown in FIG. 9 is almost identical to the conventional procedure shownin FIG. 1, with the some modifications which are indicated in bold fontin FIG. 9. As indicated, the first mobile equipment 710 may signal tothe MME 114 that it will be running in a dual ME mode (see the“dualFlag” indications), which can be realized by including a dual modeindication in the attach request message (e.g., as part of the UEnetwork capabilities) or in the NAS security mode complete message, forexample. The MME 714 may receive this information also together with theset of authentication vectors from the HSS 728. Also, to enable thereuse of the obtained set of authentication vectors in the second attachprocedure, the MME 714 may store the set of authentication vectors in adatabase (indicated as “Dual ME Database” in the figure).

FIG. 10 illustrates a signaling diagram of a first exemplary variant ofthe second attach procedure performed by the second mobile equipment 712upon completion of the first attach procedure. The procedure shown inFIG. 10 is again almost identical to the conventional procedure of FIG.1, but is different to the extent that a set of authentication vectorsstored in the first attach procedure is reused. When the MME 714 thusreceives the second attach request, it may notice that there is alreadyan active context for the same IMSI. If not already aware of it from thefirst attach procedure, the MME 714 may verify that the wireless device702 is allowed to operate in dual mode. This can be done using a dualmode indication included in the second attach request or by obtainingcorresponding confirmation from the HSS 728 (optionally, also obtaininga maximum number of simultaneously allowed contexts). The MME 714 maythen retrieve the set of authentication vectors from the Dual MEDatabase for the purpose of authenticating the second mobile equipment712. In one variant, the MME 714 may select the same authenticationvector from the set of authentication vectors as for the first mobileequipment 710 and may send an authentication request to the secondmobile equipment 712 with the same RAND and AUTN as in the first attachprocedure. The single subscriber identity module 713 may verify that thesame AUTN is received, generate or reuse the response RES, use the samekeys (CK and IK) as for the first mobile equipment 710, and provide theresults to the second mobile equipment 712. From this point on, thesecond mobile equipment 712 may proceed with the attach procedure basedon the provided results in the conventional manner.

In another variant, the MME 714 may select a different authenticationvector from the set of authentication vectors for the second mobileequipment 712 so that the single subscriber identity module 713 gets afresh authentication vector and performs a regular AKA procedure. Inthis way, necessary modifications to the second mobile equipment 712 andthe single subscriber identity module 713 may be minimized. The firstmobile equipment 710 and the second mobile equipment 712 may in thiscase have different keys and the MME 714 may need to provide amaintenance indication to the wireless device 702 to make sure that thepreviously established context for the first mobile equipment 710 iskept alive and not discarded.

FIG. 11 illustrates a signaling diagram of a second exemplary variant ofthe second attach procedure. This variant differs to the extent thatauthentication-related data stored by the wireless device 702 in thefirst attach procedure is reused by including data derived from thestored authentication-related data. In this variant, the USIMapplication 713 may provide the second mobile equipment 712 with thesame CK, IK and RAND as used for the first mobile equipment 710 (and,optionally, other relevant parameters for key generation, such as UEcapabilities and counters). The second mobile equipment 712 may thengenerate the K_(ASME), sign the received RAND with it and send thesecond attach request including the signed RAND. The signed RAND mayimplicitly act as dual mode indication for the MME 714, or there may bean explicit dual mode indication as described above. The MME 714 maythen verify that the RAND is the one used by the first mobile equipment710 and is signed by the K_(ASME) of the first mobile equipment 710. Thecontext of the first mobile equipment 710 may be identified based on theIMSI. If successfully verified, the MME 714 may consider the secondmobile equipment 712 authenticated. The remaining portion of the attachprocedure may again continue in the conventional manner.

FIG. 12 illustrates a signaling diagram of a third exemplary variant ofthe second attach procedure. This variant differs to the extent that, aspart of the second attach procedure, an authentication request forauthenticating the second mobile equipment 712 is sent to the firstmobile equipment 710, wherein the first mobile equipment 710 triggersverification of whether the authentication request belongs to the secondattach procedure. The MME 714 thus sends the authentication request to adifferent mobile equipment from where it received the attach request.The authentication request may optionally contain a dual modeindication. The first mobile equipment 710 may verify that the receiveddual mode indication corresponds to the actions of the second mobileequipment 712, which may simply be done by checking that the secondmobile equipment 712 has sent an attach request or, if the dual modeindication corresponds to a random number, by checking that the receiveddual mode indication is the same as the one sent by the second mobileequipment 712 in the second attach request. In this way, attacks byrandom users trying to exploit the dual mode function and attempting topretend to be the second mobile equipment 712 may be blocked. Theauthentication request may then be forwarded to the USIM application 713which may provide the keys and response RES to both the first mobileequipment 710 and the second mobile equipment 712. In the shown example,the first mobile equipment 710 then responds to the authenticationrequest, wherein, upon successful authentication, the procedurecontinues in the conventional manner.

FIG. 13 illustrates a signaling diagram of a fourth exemplary variant ofthe second attach procedure, which is identical to the third exemplaryvariant of FIG. 12, with the only difference being that the USIMapplication 713 provides the keys and response RES to the second mobileequipment 712 only, which then answers the authentication requestinstead of the first mobile equipment 710.

FIGS. 14 and 15 illustrate signaling diagrams of exemplary proceduresfor providing a redundancy indication from the MME 714 to the PGW 716 toindicate to the PGW 716 that data received from the first mobileequipment 710 and the second mobile equipment 712 is transferredredundantly, thereby enabling the PGW 716 to link contexts for the firstmobile equipment 710 and the second mobile equipment 712 together.Corresponding signaling may be performed using a GTP-C protocol betweenthe MME 714, the corresponding SGW 720/724 and the PGW 716. The MME 714may initiate creation of a session over the GTP-C protocol in a sessioncreation request message using information elements, such as:

IMSI,

MSISDN,

ME 1 Identity

. . .

As mentioned above, conventional cellular networks may implement abehavior according to which an already existing session is deletedbefore creating a new session if the creation request collides with theexisting session. Since, for redundant data transfer according to thetechnique presented herein, two sessions may need to be mapped to thesame IMSI number, modifications to conventional signaling may beapplied.

In one such variant, the creation of two sessions using the same IMSI(linking two contexts together) may be implemented using a redundancyindication provided in the form of an extension field included in asession creation request message of an existing session creationprotocol. Such situation is shown in FIG. 14, where a conventionalPacket Data Network (PDN) context is extended by the additional field“UE Redundant status” in the SGW 720/724 (i.e., PDN context [IMSI, EPS,Bearerld, UE Redundant status]), wherein the additional field may berepresented by a Boolean value (e.g., 0=disabled, 1=enabled), forexample. Further, as shown in the figure, a flag may be used in thesession creation request message concerning the second mobile equipment712 to indicate that the IMSI number of the new session request willalready have an established PDN context and that a new PDN contextshould be added to the same IMSI number.

In another variant, the creation of two sessions using the same IMSI maybe implemented using a redundancy indication provided in the form of adedicated session creation request message extending an existing sessioncreation protocol. In such a new session creation request message,additional information elements may be used, such as:

IMSI,

MSISDN,

ME Identity for ME 1

ME Identity for ME 2

. . .

Information elements “ME Identity for ME 1” and “ME Identity for ME 2”may here provide information enabling the PGW 716 to set up two PDNcontexts for the same IMSI number and link them together. Such situationis illustrated in FIG. 15.

As has become apparent from the above, the present disclosure provides atechnique for providing reliable wireless communication between awireless device and a cellular network. According to the presentedtechnique, two mobile equipments may be attached to a single subscriberidentity module and share the common security credentials used forauthentication and control signaling. Both mobile equipments may use thesame subscriber identity to enable the cellular network to perceive bothmobile equipments as a single entity. Traffic may be merged and split onboth the side of the wireless device and the side of the network,providing user plane redundancy in the core network and the accessnetwork, while applications or services running on top may be agnosticof the redundant data transfer. Increased availability and reliabilityof communication for applications and services running on top may thusbe achieved and the negative effects of communication link, device, nodeor base station failures (software and/or hardware failures), or anyother kind of malfunctions may be minimized. This may especially beadvantageous in the industrial manufacturing domain. As both mobileequipments may use the same subscriber identity module to communicatethe security parameters used to authenticate against the network and, inparticular, since some of these security parameters may be reused,signaling required in the AKA procedures of the wireless device may bereduced. Also, the technique presented herein enables mapping two PDNcontexts to a single IMSI number and thereby allows redundancy for userplane traffic in the core network by the use of multiple PDNconnectivity links for a single IMSI.

It is believed that the advantages of the technique presented hereinwill be fully understood from the foregoing description, and it will beapparent that various changes may be made in the form, constructions andarrangement of the exemplary aspects thereof without departing from thescope of the invention or without sacrificing all of its advantageouseffects. Because the technique presented herein can be varied in manyways, it will be recognized that the invention should be limited only bythe scope of the claims that follow.

The invention claimed is:
 1. A method for providing reliable wirelesscommunication between a wireless device and a cellular network, thewireless device comprising a first mobile equipment and a second mobileequipment sharing a single subscriber identity module, the method beingperformed by the wireless device and comprising: sending a first attachrequest as part of a first attach procedure to the cellular networkusing the first mobile equipment via a first base station to establish afirst communication channel to the cellular network; and sending asecond attach request as part of a second attach procedure to thecellular network using the second mobile equipment via a second basestation to establish a second communication channel to the cellularnetwork, wherein the first attach procedure and the second attachprocedure are performed using a same subscriber identity provided by thesingle subscriber identity module and wherein, upon completion of thefirst attach procedure and the second attach procedure, datacommunicated between the wireless device and the cellular network istransferred redundantly over the first communication channel and thesecond communication channel.
 2. The method of claim 1, wherein thewireless device serves as wireless communication gateway for a baseapplication, wherein data transferred redundantly from the wirelessdevice to the cellular network originates from the base application. 3.The method of claim 2, wherein data originating from the baseapplication is duplicated by a redundancy component before beingtransferred to the cellular network over the first communication channeland the second communication channel.
 4. The method of claim 2, whereinduplicate data transferred from the cellular network to the wirelessdevice over the first communication channel and the second communicationchannel is dropped by a redundancy component before forwarding thetransferred data to the base application.
 5. The method of claim 1,wherein, in at least one of the first and the second attach procedure, adual mode indication is sent from the wireless device to the cellularnetwork indicating that the wireless device intends to transfer dataredundantly over the first communication channel and the secondcommunication channel.
 6. The method of claim 1, whereinauthentication-related data used in the first attach procedure is reusedin the second attach procedure.
 7. The method of claim 6, wherein theauthentication-related data reused in the second attach procedurecomprises a set of authentication vectors stored by the cellular networkin the first attach procedure.
 8. The method of claim 7, wherein, fromthe set of authentication vectors, an authentication vector differentfrom an authentication vector used in the first attach procedure is usedin the second attach procedure.
 9. The method of claim 8, wherein anauthentication request sent from the cellular network to the secondmobile equipment includes a maintenance indication indicating to thewireless device to maintain a context already established for the firstmobile equipment in the first attach procedure.
 10. The method of claim6, wherein the authentication-related data reused in the second attachprocedure comprises authentication-related data stored by the wirelessdevice in the first attach procedure.
 11. A computer program productcomprising a non-transitory computer readable medium storing computerprogram instructions for performing the method of claim 1 when thecomputer program product is executed on one or more computing devices.12. A wireless device for providing reliable wireless communication to acellular network, the wireless device comprising a first mobileequipment and a second mobile equipment sharing a single subscriberidentity module, and the wireless device comprising at least oneprocessor and at least one memory, the at least one memory containinginstructions executable by the at least one processor such that thewireless device is operable to perform the method of claim
 1. 13. Amethod for providing reliable wireless communication between a wirelessdevice and a cellular network, the method being performed by a node ofthe cellular network and comprising: receiving a first attach requestfrom a first mobile equipment of the wireless device via a first basestation as part of a first attach procedure to establish a firstcommunication channel between the cellular network and the wirelessdevice; receiving a second attach request from a second mobile equipmentof the wireless device via a second base station as part of a secondattach procedure to establish a second communication channel between thecellular network and the wireless device, wherein, in the first attachprocedure and the second attach procedure, a same subscriber identity isused and wherein, upon completion of the first attach procedure and thesecond attach procedure, data communicated between the wireless deviceand the cellular network is transferred redundantly over the firstcommunication channel and the second communication channel.
 14. Themethod of claim 13, wherein the second attach request is received uponcompletion of the first attach procedure.
 15. The method of claim 13,wherein, in at least one of the first and the second attach procedure, adual mode indication is received by the node from the wireless deviceindicating that the wireless device intends to transfer data redundantlyover the first communication channel and the second communicationchannel.
 16. The method of claim 13, wherein authentication-related dataused in the first attach procedure is reused in the second attachprocedure.
 17. A node of a cellular network for providing reliablewireless communication between a wireless device and the cellularnetwork, the node comprising at least one processor and at least onememory, the at least one memory containing instructions executable bythe at least one processor such that the node is operable to perform themethod of claim
 13. 18. A method for providing reliable wirelesscommunication between a wireless device and a cellular network, themethod being performed by a gateway of the cellular network andcomprising: receiving first data over a first communication channelestablished between a first mobile equipment of the wireless device andthe cellular network via a first base station; receiving second dataover a second communication channel established between a second mobileequipment of the wireless device and the cellular network via a secondbase station, wherein the first data and the second data are associatedwith a same subscriber identity and wherein the first data and thesecond data are transferred redundantly over the first communicationchannel and the second communication channel; and dropping duplicatedata from the first data and the second data before forwarding thetransferred data to a network-side application.
 19. The method of claim18, wherein data to be transferred from the network-side application tothe wireless device is duplicated by the gateway before beingtransferred to the wireless device over the first communication channeland the second communication channel.
 20. A gateway of a cellularnetwork for providing reliable wireless communication between a wirelessdevice and the cellular network, the gateway comprising at least oneprocessor and at least one memory, the at least one memory containinginstructions executable by the at least one processor such that thegateway is operable to perform the method of claim 18.